1. Field of the Invention
The present invention relates to a device for processing of inputs and outputs of digital contents to and from a recording medium and a contents protection program.
2. Description of the Prior Art
Along with the progress of digital technology in recent years, it has become possible for various digital devices including personal computers and mobile telephones to handle a wide variety of contents such as documents, still pictures, moving pictures and music as digital contents. Since such digital contents are sent every day to electronic devices in large quantities, it is impossible to save all the incoming digital contents in the memory unit of a digital device. For this reason, many digital devices are able to store digital contents on a readable/writable and detachable recording medium.
However, as the specifications of the storage formula of any recording medium are standardized and made open, anybody can readily make a copy of the contents of a given recording medium by use of a personal computer. This makes it impossible to protect the copyright of the producer of the digital contents, and therefore it is called upon to develop a technique for protecting the contents of recording media from the standpoint of copyright protection.
Known formulas for preventing illegal copying of contents include one by which contents are enciphered with an enciphering key utilizing a medium ID for uniquely identifying a recording medium within the recording medium and recording the enciphered contents on the recording medium and, at the time of reading the contents out, a formula requiring the medium ID used at the time of enciphering is used. In this way, even if contents are illegitimately copied onto another recording medium, the contents cannot be correctly read out because there is no right medium ID, and illegal copying of contents can be thereby prevented.
This formula, however, allows playback of the recording medium on which legitimately written contents are stored with any one of a plurality of compatible devices, and accordingly involves the problem that the recording medium can be illegitimately transferred or resold to another person or the contents can be used by a plurality of persons.